Intravascular filter with debris entrapment mechanism

ABSTRACT

Apparatus for filtering and entrapping debris in the vascular system of a patient, the apparatus including a filter to allow blood to flow therethrough and to restrict passage of debris, wherein the filter captures debris carried in a first direction of blood flow. The apparatus further includes an entrapment mechanism which allows passage of debris and blood therethrough, in the first direction of blood flow and prevents debris passage in a second direction. The entrapment mechanism and filter allow blood and debris therethrough in the first direction of blood flow. The entrapment mechanism prevents debris flow in the second direction of blood flow. A method for filtering and entrapping debris in the vascular system includes inserting the apparatus into the vascular system, allowing blood and debris carried therein to flow through the entrapment mechanism, and removing the apparatus and accumulated debris from the vascular system.

REFERENCE TO PENDING PRIOR PATENT APPLICATION

This application is a divisional application of a U.S. patentapplication Ser. No. 10/772,782 now U.S. Pat. No. 7,758,606, filed Feb.5, 2004, which patent application is a continuation of U.S. patentapplication Ser. No. 09/896,258, filed Jun. 29, 2001, now U.S. Pat. No.6,692,513, which '258 application claimed the benefit of prior U.S.Provisional Patent Application Ser. No. 60/215,542, filed Jun. 30, 2000by Richard B. Streeter et al. for INTRAVASCULAR FILTER WITH DEBRISENTRAPMENT MECHANISM, which patent application is hereby incorporatedherein by reference, and of prior U.S. Provisional Patent ApplicationSer. No. 60/231,101, filed Sep. 8, 2000 by Richard B. Streeter et al.for INTRAVASCULAR FILTER WITH DEBRIS ENTRAPMENT MECHANISM, which patentapplication is hereby incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to intravascular filtering apparatus and methodsin general, and more particularly to apparatus and methods for filteringand irreversibly entrapping embolic debris from the vascular systemduring an intravascular or intracardiac procedure.

BACKGROUND OF THE INVENTION

Intracardiac and intravascular procedures, whether performedpercutaneously or in an open, surgical, fashion, may liberateparticulate debris. Such debris, once free in the vascular system, maycause complications including vascular occlusion, end-organ ischemia,stroke, and heart attack. Ideally, this debris is filtered from thevascular system before it can travel to distal organ beds.

Using known filter mechanisms deployed in the arterial system, debris iscaptured during systole. There is a danger, however, that such debrismay escape the filter mechanism during diastole or during filterremoval. Apparatus and methods to reduce debris escape during diastoleor during filter removal may be desirable to reduce emboliccomplications.

SUMMARY OF THE INVENTION

An object of the invention is to provide a filtering mechanism thatirreversibly entraps debris therein.

Another object of the invention is to provide a filtering mechanism thatpermanently captures debris from the intravascular system of a patient.

A further object of the invention is to provide a filtering mechanismwith greater ability to collect debris in the intravascular system of apatient to decrease the number of complications attributable to suchdebris.

Another further object of this invention is to provide a filter holdingmechanism suitable to be secured to a retractor used to create access tothe heart and surrounding structures during heart surgery procedures.

A still further object is to provide a method for using a filteringmechanism in the intravascular system of a patient to permanentlycapture debris therefrom.

Another still further object of the present invention is to provide amethod for introducing a filtering device in the aorta downstream of theaortic valve to restrict the passage of emboli while allowing blood toflow through the aorta during cardiovascular procedures, and to entrapdebris collected in the filter so as to prevent its escape duringcardiac diastole or during manipulation, repositioning or removal of thedevice from the aorta.

With the above and other objects in view, as will hereinafter appear,there is provided apparatus for debris removal from the vascular systemof a patient, said apparatus comprising: a filtering device having aproximal side and a distal side said filter being sized to allow bloodflow therethrough and to restrict debris therethrough and said filterhaving a first given perimeter, wherein blood flow in a first directionpasses from the proximal side to the distal side of the filteringdevice; an entrapment mechanism having a proximal side and a distalside, the entrapment mechanism forming a selective opening to allowdebris and blood flow passage in the first direction from the proximalside to the distal side therethrough, the selective opening having arestriction mechanism to prevent debris passage in a second directionopposite to said first direction the selective opening having a secondgiven perimeter, the first given perimeter and the second givenperimeter being deployed within the vascular system so as to form achamber between the distal side of the entrapment mechanism and theproximal side of the filtering device, wherein the entrapment mechanismallows blood flow and debris to pass therethrough in the firstdirection, the filtering device allows blood flow to pass therethroughin the first direction, the restriction mechanism prevents debris frompassing back through said selective opening in a second directionopposite to the first direction and the chamber contains the debrisreceived through the entrapment mechanism so as to prevent the escape ofthe debris therein by said filtering device in the first direction andsaid restriction mechanism in said second direction.

In accordance with another further feature of the invention there isprovided a method for filtering and entrapping debris from the vascularsystem of a patient, the method comprising: providing apparatus forfiltering and entrapping debris from the vascular system of a patient,the apparatus comprising: a filter device being sized to allow bloodflow therethrough and to restrict passage of debris therethrough, andthe filter device having a first given perimeter, a proximal side and adistal side; and wherein the filtering device captures debris carried ina first direction of blood flow from the proximal side to the distalside thereof on the proximal side of the filter device; an entrapmentmechanism having a proximal side and a distal side, the entrapmentmechanist including a selective opening to allow passage of blood anddebris therethrough, the selective opening being configured to allowpassage of blood and debris carried therein therethrough in the firstdirection of blood flow from the proximal side to the distal side of theentrapment mechanism, the selective opening having a restrictionmechanism to prevent debris passage from the distal side to the proximalside of the entrapment mechanism in a second direction opposite to thefirst direction, the selective opening forming a second given perimeter,and the first given perimeter and the second given perimeter beingdeployed within the vascular system so as to form a chamber between thedistal side of the entrapment mechanism and the proximal side of thefiltering device; wherein the entrapment mechanism allows blood anddebris carried therein therethrough in the first direction of bloodflow, the filtering device allows blood therethrough in the firstdirection of blood flow, and the restriction mechanism prevents debrisback through the selective opening in the second direction of blood flowopposite to the first direction of blood flow such that the chamberentraps the filtered debris received therein for debris removal from thevascular system of the patient; inserting said apparatus into thevascular system of the patient; allowing blood and debris carriedtherein to flow through the entrapment mechanism, and into the chamber;and removing the apparatus from the vascular system of the patient.

The above and other features of the invention, including various noveldetails of construction and combinations of parts and method steps willnow be more particularly described with reference to the accompanyingdrawings and pointed out in the claims. It will be understood that theparticular devices and method steps embodying the invention are shown byway of illustration only and not as limitations of the invention. Theprinciples and features of this invention may be employed in various andnumerous embodiments without departing from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will bemore fully disclosed or rendered obvious by the following detaileddescription of the preferred embodiments of the invention, which are tobe considered together with the accompanying drawings wherein likenumbers refer to like parts, and further wherein:

FIG. 1A is a perspective view of a deployable entrapment filteringdevice for debris removal showing the filtering device in its fullydeployed shape as released, from its cannula into the blood stream of apatient;

FIG. 1B is an exploded perspective view of the deployable entrapmentfiltering device of FIG. 1A showing the components thereof;

FIG. 1C is a schematic cross-sectional illustration depicting thedeployable entrapment filtering device of FIGS. 1A and 1B during cardiacsystole;

FIG. 1D is a schematic cross-sectional illustration depicting thedeployable entrapment filtering device of FIGS. 1A and 1B during cardiacdiastole;

FIG. 2A is an exploded perspective view of a deployable entrapmentfiltering device for debris removal showing the components thereofincluding a set of filter mesh entrapment leaflets;

FIG. 2B is a schematic cross-sectional illustration depicting thedeployable entrapment filtering device of FIG. 2A during cardiacsystole;

FIGS. 3A-3D are a series of schematic illustrations depicting a methodof using the deployable entrapment filtering device of FIGS. 2A and 2B;

FIG. 4A is an exploded perspective view of a deployable entrapmentfiltering device for debris removal showing the components thereofincluding a set of non-porous valve leaflets;

FIG. 4B is a schematic cross-sectional illustration depicting thedeployable entrapment filtering device of FIG. 4A during cardiacsystole;

FIGS. 5A-5D are a series of schematic illustrations depicting a methodof using the deployable entrapment filtering device of FIGS. 4A and 4B;and

FIGS. 6A-6D are schematic illustrations depicting an orthogonallydeployable valve/filter apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A filtration and entrapment apparatus 5 is shown in FIGS. 1A-5D fordebris removal from the vascular system of a patient. Filtration andentrapment apparatus 5 generally includes a filter device 10 and anentrapment mechanism 15. Filtration and entrapment apparatus 5 can beused to filter emboli during a variety of intravascular or intracardiacprocedures, including, but not limited to, the following procedures:vascular diagnostic procedures, angioplasty, stenting, angioplasty andstenting, endovascular stent-graft and surgical procedures for aneurysmrepairs, coronary artery bypass procedures, cardiac valve replacementand repair procedures, and carotid endardarectomy procedures.

Now looking at FIGS. 1A-1D, a preferred embodiment of the presentinvention is shown with filtration and entrapment apparatus 5 asdescribed herein below.

FIG. 1A depicts the profile of filtration and entrapment apparatus 5 inits fully deployed shape, with filter device 10 and entrapment mechanism15 released from cannula 20 into the blood stream (not shown). Prior todeployment, filter device 10 and entrapment mechanism 15 are collapsedwithin cannula 20, e.g., by moving the proximal end 25A proximally alongcenter post 50.

FIG. 1B depicts the primary components of filtration and entrapmentapparatus 5 comprising filter device 10 and entrapment mechanism 15 inattachment to deployable frame 25. In the present embodiment of theinvention, filter device 10 comprises a filter mesh bag 30, andentrapment mechanism 15 comprises a piece of coarse mesh 35 and a set ofentrapment flaps 40.

FIG. 1C depicts filtration and entrapment apparatus 5 deployed within anaorta 45 during cardiac systole. Blood and debris flow through openeddeployable frame 25, across course mesh 35, between and throughentrapment flaps 40 and into the end of the filter mesh bag 30.Entrapment flaps 40 ensure unidirectional flow of blood and debris intofilter mesh bag 30.

FIG. 1D depicts filtration and entrapment apparatus 5 within the aorta45 responding to any retrograde flow of blood and/or back pressurewithin the aorta 45 during cardiac diastole. The back flow of bloodand/or back pressure causes filter mesh bag 30 to partially deform andentrapment flaps 40 to close against coarse mesh 35. Coarse mesh 35 isof a structure adequate to permit the free flow of blood and debristhrough it and into filter mesh bag 30, and serves as a supportingstructure against which entrapment flaps 40 can close and remain in aclosed position to prevent the escape of embolic debris.

Still looking at FIGS. 1A-1D, it should also be appreciated that theentrapment flaps 40 may be attached to structures other than, deployableframe 25, e.g., the entrapment flaps 40 may be attached to a center post50, or to coarse mesh 35, etc. Furthermore, if desired, entrapment flaps40 may be biased closed or biased open. In addition, entrapmentmechanism 15 may consist of one or more flaps 55, and have aconfiguration including, but not limited to, a single disk diaphragm(not shown), a semi-lunar configuration (not shown), a gill slitconfiguration (not shown), a multi-leaflet flap configuration (notshown), etc.

It should also be appreciated that, while in the foregoing descriptionthe apparatus shown in FIGS. 1A-1D has been described in the context offunctioning as a filter, it may also function as a one-way check valve.To the extent that the apparatus shown in FIGS. 1A-1D is intended tofunction primarily as a one-way check valve, filter mesh bag 30 (seeFIG. 1B) may be retained or it may be omitted.

Looking next at FIGS. 2A and 2B, there is shown an alternative form ofthe present invention as a bidirectional flow filtration and entrapmentapparatus 105. Bidirectional flow filtration and entrapment apparatus105 of FIGS. 2A and 2B generally comprises a filter device 110 and anentrapment mechanism 115 delivered by a cannula 120 to the interior of avascular structure 122 (see FIGS. 3A-3D); a deployable filter frame 125;a filter bag 130 attached to the perimeter of deployable filter frame125; a compliant, soft outer cuff 135 (preferably formed out of abiologically inert material such as Teflon, Dacron, Silastic, etc.) forsealing filtration and entrapment apparatus 105 against the inner wallof vascular structure 122 when deployable filter frame 125 is expanded;entrapment leaflets 140, preferably in the form of a fine filter mesh; acenter post 150 (preferably formed out of steel or the equivalent)passing across the interior of the deployable filter frame 125; a hingeline 155 on entrapment leaflets 140, connected to center post 150, forpermitting the entrapment leaflets 140 to open and close; co-aptationstrands 160 extending across the interior of deployable filter frame 125and providing a seat against which entrapment leaflets 10 may closeduring diastole; and a perimeter seal 165 (preferably formed out ofexpanded Teflon or the like). Perimeter seal 165 acts like a step tohelp support entrapment leaflets 140 during diastole.

In addition, it should also be appreciated that soft outer cuff 135 maycomprise a radially expandable mechanism (e.g., a balloon, adecompressed sponge, a spring loaded leaflet, etc.) for sealingfiltration and entrapment apparatus 105 against the inner wall ofvascular structure 122.

As noted above, entrapment leaflets 140 are preferably formed out of afine filter mesh. This filter mesh is sized so that it will pass bloodtherethrough but not debris. Furthermore, this filter mesh is sized sothat it will provide a modest resistance to blood flow, such that theentrapment leaflets will open during systole and close during diastole.By way of example but not limitation, the filter mesh may have a poresize of between about 40 microns and about 300 microns.

FIGS. 3A-3D illustrate operation of bidirectional flow filtration andentrapment apparatus 105 shown in FIGS. 2A and 2B. More particularly,cannula 120 of deployable filtration and entrapment apparatus 105 isfirst inserted through a small incision 170 in the wall of the vascularstructure 122 (see FIG. 3A). Then deployable filter frame 125 isdeployed (see FIG. 3B). Thereafter, during systole (see FIG. 3C), bloodflows through deployable filter frame 125, forcing entrapment leaflets140 open, and proceeds through filter bag 130. Any debris contained inthe blood is captured by filter bag 130 and thereby prevented frommoving downstream past bidirectional flow filtration and entrapmentapparatus 105. During diastole (see FIG. 3D), when the blood flowmomentarily reverses direction, entrapment leaflets 140 (shown in FIGS.2A and 2B) close, seating against co-aptation strands 160 (shown inFIGS. 2A and 2B) extending across the interior of deployable filterframe 140 (shown in FIGS. 2A and 2B). The blood passes through the finemesh of entrapment leaflets 140 (shown in FIGS. 2A and 2B), beingfiltered as it passes, thus permitting coronary profusion to take placeduring the diastolic phase. The fine mesh of entrapment leaflets 140(shown in FIGS. 2A and 2B) prevents debris from passing back throughbidirectional flow filtration and entrapment apparatus 105.

It should also be appreciated that with bidirectional flow filtrationand entrapment apparatus 105 of FIGS. 2A, 2B and 3A-3D, entrapmentleaflets 140 may be attached to structures other than center post 150,e.g., they may be attached to co-aptation strands 160, or to deployablefilter frame 125, etc. Furthermore, if desired, entrapment leaflets 140may be biased closed, or biased open. In addition, entrapment mechanism15 may consist of one or more flaps (not shown), and have aconfiguration including, but not limited to, a single disk diaphragm(not shown), a semi-lunar configuration (not shown), a gill slitconfiguration (not shown), a multi-leaflet flap configuration (notshown), etc.

Looking next at FIGS. 4A and 4B, there is shown a deployablevalve/filter apparatus 205. Deployable valve/filter apparatus 205 ofFIGS. 4A and 4B generally comprises a filter device 210 and a valveentrapment mechanism 215 delivered by a cannula 220 to the interior ofthe vascular structure 222; a deployable valve/filter frame 225; afilter bag 230 attached to the perimeter of deployable valve/filterframe 225; a compliant, soft outer cuff 235 (preferably formed out of abiologically inert material such as Teflon, Dacron, Silastic, etc.) forsealing the filter device 210 against the inner wall of vascularstructure 222 when deployable valve/filter frame 225 is expanded; valveleaflets 240, preferably in the form of a blood-impervious material; acenter post 250 (preferably formed out of steel or the equivalent)passing across the interior of deployable valve/filter frame 225; ahinge line 255 on valve leaflets 240, connected to center post 250, forpermitting valve leaflets 240 to open and close; co-aptation strands 260extending across the interior of deployable valve/filter frame 225 andproviding a seat against which valve leaflets 240 may close duringdiastole; and a perimeter seal 265 (preferably formed out of expandedTeflon or the like). Perimeter seal, 265 acts like a step tohelp-support valve leaflets 240 during diastole.

In addition, it should also be appreciated that soft outer cuff 235 maycomprise a radially expandable mechanism (e.g., a balloon, adecompressed sponge, spring loaded leaflet, etc.) for sealing deployablevalve/filter apparatus 205 against the inner wall of vascular structure222.

FIGS. 5A-5D illustrate operation of deployable valve/filter apparatus205 of FIGS. 4A and 4B. More particularly, valve/filter apparatus 205 isfirst inserted through a small incision 270 in the wall of the vascularstructure 222 (see FIG. 5A). Then deployable valve/filter frame 225 isdeployed (see FIG. 5B). Thereafter, during systole (see FIG. 5C), bloodflows through deployable valve/filter frame 225, forcing valve leaflets240 open, and proceeds through filter bag 230. Any debris contained inthe blood is captured by filter bag 230 and thereby prevented frommoving downstream past valve/filter apparatus 205. During diastole (seeFIG. 5D), when the blood flow momentarily reverses direction, valveleaflets 240 (shown in FIGS. 4A and 4B) close, seating againstco-aptation strands 260 (shown in FIGS. 4A and 4B) across the interiorof deployable valve/filter frame 225 (shown in FIGS. 4A and 4B). Theclosed leaflets 240 (shown in FIGS. 4A and 4B) prevent blood frompassing back through the valve/filter frame 225 (shown in FIGS. 4A and4B).

It should also be appreciated that with valve/filter apparatus 205 shownin FIGS. 4A, 4B and 5A-5D, valve leaflets 240 may be attached tostructures other than center post 250, they may be attached toco-aptation strands 260, or to deployable valve filter frame 225, etc.Furthermore, if desired, valve leaflets 240 may be biased closed, orbiased open. In addition, valve entrapment mechanism 215 may consist ofone or more flaps (not shown), and have a configuration including, butnot limited to, a single disk diaphragm (not shown), a semi-lunarconfiguration (not shown), a gill slit configuration (not shown), amulti-leaflet flap configuration (not shown), etc.

Looking next at FIGS. 6A-6B, there is shown an orthogonally deployablevalve/filter apparatus 305. Orthogonally deployable valve/filterapparatus 305 of FIGS. 6A-6D generally comprises a filter device 310 anda valve entrapment mechanism 315 deployed at an angle substantiallyorthogonal to an axis 318 of a cannula 320, such as a catheterintroduced to the vascular system at a location which may be remote fromthe point of operation, in the interior of a vascular structure 322; adeployable valve/filter frame 325; a filter bag 330 attached to theperimeter of deployable valve/filter frame 325; a compliant, soft outercuff 335 (preferably formed out of a biologically inert material such asTeflon, Dacron, Silastic, etc.) for sealing the filter device 310against the inner wall of vascular structure 322 when deployablevalve/filter frame 325 is expanded; valve leaflets 340, preferably inthe form of a blood-impervious material, having a first portion 350 inattachment to deployable valve/filter frame 325, and a second portion355 separable from deployable valve/filter frame 325, so as to allowvalve leaflets 340 to open and close; and a mesh material 360 extendingacross the interior of deployable valve/filter frame 325 and providing aseat against which valve leaflets 340 may close during diastole. Inaddition, it should be appreciated that mesh material 360 may comprisecoaptation strands such as coaptation strands 160 as first shown in FIG.2A.

In addition, it should also be appreciated that soft outer cuff 335 maycomprise a radially expandable mechanism (e.g., a balloon, adecompressed sponge, a spring loaded leaflet, etc.) for sealingorthogonally deployable valve/filter apparatus 305 against the innerwall of vascular structure 322.

In addition, it should also be appreciated that valve entrapmentmechanism 315 may be mounted for blood flow in either direction withinvascular structure 322.

FIGS. 6A-6D illustrate operation of deployable valve/filter apparatus305. More particularly, deployable valve/filter apparatus 305 is firstinserted through the interior of vascular structure 322 to a desiredlocation (see FIG. 6C). Then deployable valve/filter frame 325 isdeployed (see FIG. 6D). Thereafter, during systole (see FIG. 6A), bloodflows through deployable valve/filter frame 325, forcing valve leaflets340 open, and proceeds through filter bag 330. Any debris contained inthe blood is captured by filter bag 330 and thereby prevented frommoving downstream past deployable valve/filter apparatus 305. Duringdiastole (see FIG. 6B), when the blood flow momentarily reversesdirection, valve leaflets 340 close, seating against mesh material 360across the interior of deployable filter frame 340. The closed leaflets340 prevent blood from passing back through the valve/filter frame 325.

It should also be appreciated that with valve/filter apparatus 305 shownin FIGS. 6A-6D, valve leaflets 340 may be attached to structures otherthan deployable valve/filter frame 325, e.g., they may be attached tomesh material 260, or to cannula 320, etc. Furthermore, if desired,valve leaflets 340 may be biased closed, or biased open. In addition,valve entrapment mechanism 315 may consist of one or more flaps (notshown), and have a configuration including, but not limited to, a singledisk diaphragm (not shown), a semi-lunar configuration (not shown), agill slit configuration (not shown), a multi-leaflet flap configuration(not shown), etc.

The filter design as described herein to prevent the escape of captureddebris during diastole or filter removal may also be applied to allintravascular filters. Such a filter design may comprise a one-way valveand a filtering mesh in series. Liberated debris may pass through theone-way valve and come to rest in the filtering mesh. The one-way valveensures permanent entrapment of debris. Potential applications of suchan apparatus extend to all percutaneous and surgical procedures on theheart and vascular system, including open heart surgery, balloondilatation of cardiac valves and arteries, deployment of stents inarteries, diagnostic catheterizations, and other cardiac and vascularprocedures. Advantages of such a system include more complete collectionof liberated debris, with a resulting decrease in the complicationsattributable to such debris.

1. A method for filtering and entrapping debris from the vascular systemof a patient, said method comprising: introducing an apparatus forfiltering and entrapping debris into the vascular system of a patient,said apparatus comprising: a filter device being sized to allow bloodflow therethrough and to restrict passage of debris therethrough, andsaid filter device having a first given perimeter, a proximal side and adistal side; and wherein said filtering device captures debris carriedin a first direction of blood flow from said proximal side to saiddistal side thereof on said proximal side of said filter device; anentrapment device having a proximal side and a distal side, saidentrapment mechanism including a selective opening of a size to allowpassage of blood and debris therethrough, said selective openingallowing passage of blood and debris carried therein therethrough insaid first direction of blood flow from said proximal side to saiddistal side of said entrapment mechanism, said selective opening havinga restriction element to prevent debris passage from said distal side tosaid proximal side of said entrapment device that is operativelyprovided to change a size of the selective opening without changing thesize of the entrapment device as deployed so as to prevent debrispassage back through said selective opening from said distal side tosaid proximal side of said entrapment device in a second directionopposite to said first direction, said selective opening forming asecond given perimeter; wherein said entrapment device allows blood anddebris carried therein therethrough in said first direction of bloodflow, said filtering device allows blood therethrough in said firstdirection of blood flow, and said restriction element prevents debrisback through said selective opening in said second direction of bloodflow opposite to said first direction of blood flow such that saidchamber entraps the filtered debris received therein for debris removalfrom the vascular system of the patient; advancing said apparatus alongthe vascular system of the patient to a point of deployment; andallowing blood and debris carried therein to flow through saidentrapment device, and into said chamber.
 2. A method according to claim1 further comprising the step of making an opening in a wall of aportion of the vascular system prior to the step of introducing saidapparatus into the vascular system of the patient wherein said apparatusis inserted through said opening.
 3. A method according to claim 2wherein the portion is the aorta of the patient.
 4. A method accordingto claim 1 further comprising the step of removing said apparatus fromthe vascular system of the patient.
 5. A method according to claim 4wherein said apparatus maintains entrapment of debris during the step ofremoving said apparatus from the vascular system of the patient.